Problems associated with the Z-fold region of defibrillation electrodes

To examine performance failures of automatic external defibrillator (AED) self-adhesive electrodes, a retrospective analysis of patient reports and electrodes was conducted in a suburban emergency medical service (EMS) system. In all cases, only records from out-of-hospital cardiac arrests (OHCA) were used if the EMS was activated and an AED was used. Electrode failures were assessed as follows: 1) EMS staff returned defibrillation electrodes when they were unable to resolve repeated "Check Electrode" messages, and 2) an audit of selected records was used to determine the frequency of electrode problems during calls. Of 302 OHCA calls during the study period, 22 (7%) resulted in returned electrodes. Defects (cracks or faults) in the internal conductor were present in 37 (86%) of the 43 returned electrodes; 2 (5%) possessed dehydrated conductive gel, and in 4 (9%) electrodes no faults could be identified. Of the 21 complete sets of defective electrodes, 16 (76%) had faults in both electrodes. Chart review revealed at least one "check electrode" message occurring in 21 (60%) of 35 OHCA reports. The electrode checks were present for a total of over 83 min, representing 11% of the call times. Paramedics were required to change electrodes in 9 (26%) of the 35 cases, resolving the malfunction in all instances. Electrode malfunction appears to be a common prehospital problem; the conductor is responsible for the majority of electrode problems and is probably subjected to the most stress during storage and handling. More reliable, durable defibrillation electrodes are required for OHCA treatment. Other strategies for electrode storage and quality control are also discussed.